
def f(x):
    return x ** 5 - 15 * x ** 4 + 85 * x ** 3 - 225 * x ** 2 + 274 * x - 121
 
 
def bisection_method(low, high):
    while True:
        mid = (low + high) / 2
        if abs(f(mid)) < 1 * 10 ** -n:
            return '{:.6f}'.format(mid)
        elif f(mid) < 0:
            high = mid
        else:
            low = mid
 
 
if __name__ == '__main__':
    n = int(input())
    Low, High = 1.5, 2.4
    print(bisection_method(Low, High))